Solid-state light-emitting devices such as light emitting diodes (“LEDs”) are attractive candidates for replacing conventional light sources such as incandescent and fluorescent lamps. LEDs typically have substantially higher light conversion efficiencies than incandescent lamps, and have longer lifetimes than conventional light sources. Some types of LEDs have higher conversion efficiencies than fluorescent light sources and even higher conversion efficiencies have been demonstrated in the laboratory. For LEDs to be accepted in various lighting applications, it is important to optimize every step of the processing and achieve the highest efficiencies possible.
A problem associated with a conventional LED or an LED lighting system is power conversion from AC power to DC power because conventional LEDs use regulated DC power. LEDs typically run with constant DC current and constant DC voltage. Utility companies, on the other hand, deliver AC current and/or AC voltage. Conventional power supply such as power at electrical outlets is AC power. Currently available lighting systems in the marketplace such as incandescent light bulbs and/or halogen lights are powered by AC power.
A conventional approach for resolving DC power requirements for the LED lighting system is to provide AC-to-DC power conversion. Power conversion from AC to unregulated DC, and then converting from unregulated DC to regulated DC is often bulky and expensive. Specifically, capacitive elements used in AC-to-DC converters typically have shorter lifetime, which will affect overall lifetime of the LED lighting system.